Internal combustion engine



J y 2, 1 40- c. J. TOTH 2,206,272

INTERNAL COMBUSTION ENGINE Filad Nov. 5, 1936 INVEHTOR.

ATTORNEY Patented July 2, 1940 A Y U T D STATES PATENT oFF Application November 5, 1936, Serial No. 109,384 In ,Great Britain November 26, 1935 3 Claims. (01. 60-15 This invention relates to two-stroke internal sists essentially of two cylinders, the high pres combustion engines, and has for an object to; pro,-

sure cylinder A and the low pressure cylinder B,

vide an improved compound expansion engine. which latter is of considerably larger diameter In a two-stroke compound internal combustion than is the diameter of thehigh pressure cyl- 5 engine in accordance with the invention, the 'inder.

high pressure cylinder and the low pressure cyl- The high pressure cylinder containsthe Workinder are arranged with their axes at an acute ing piston P whichmay be of the conventional angle to form a V and the pistonsin, the two trunk piston type and it is this piston which concylinders are connected to a single crank throw. trols theopening andclosing of the cylinder ports .1. The secondary expansion, of the working fluid E whichserve for the purpose of evacuating the i0 takes place in the lower end of the low pressure high pressure cylinder of the partially expanded cylinder, that is the end nearest thetcrankshaft, Working fluid and to transfer the fluid intothe and the primary expansion takes place in the lowpressure cylinder, at appropriate times. upper end of the high pressure cylinder. The ,In the cover or headof the high pressure cylli angle between the two cylinders is such, in relainder, are located the fuel injection valve F and '25 tion to the other features of the engine, that also the corresponding valve means Owhichlattransfer of the working fluid occurs directly from ter serve the purpose of admitting precompressed the lower end of the high pressure cylinder to the scavengingand charging-air, at suitable times,

lower end of the low pressure cylinderpat the into thehigh pressurecylinder. i correct point in the cycle. i :It is to be understood that the admission valve 20 An object of the invention is the elimination, means 0 are not necessarily of the poppet valve as far as possible, of heat and pressure losses type as shown in the, illustration, but that they during transfer of the working fluid, and, with may be of any other usual form of construction, this object in view, short transfer channels are or may be also of the pistonor sleeve-valve used of such dimensions as to eliminate serious types, if desired, withoutdepartingfrom the inthrottling effects. i i vention; v i i A featureof the invention is the building up The, crankshaft of the engine has a single in a low pressure cylinder of a cushioningpres- ,crankthrow M for each group of two working i sure before working fluid is transferred to it from cylinders which form an engine unit and the so a high p essure cylinder, the arrangem ntbeing connecting rod La takes care ofthe proper con- 30 i such that at the time of transfer, the ,differnection of the high pressure piston P to the ence between the pressure in the high pressure crankthrow M. i cylinder and that in the low pressure cylinder is The low pressure cylinder B contains the workconsiderably reduced, ing;piston.Q which is preferably of the stepped A further feature of the invention is the use piston type, witha smaller portion S that may of the actual working pistons for the precomcarry the corresponding piston pin to which the pression of air which is used for scavenging and connecting rod Lb is fastened. This latter is charging air for the cylinders. Thus, theback either conveniently pinned to the connecting rod of a low pressure piston or of a high pressure pis- La of the high pressure piston or else the coni i o ton may be used for this purpose. necting rod Lb maybe fastened in any other con- 40 "The engines work on the Z-stroke cycle, the venient manner to the same crankthrow M to power stroke of a low pressure cylinder occur which the rod Laof the high pressure cylinder ring at a point about 120 to 180 later inithe isconnected. i crankshaft rotation, than does that of the cor,- The upper portion of the low pressure cylinr, responding high pressure cylinder. inder B may be totally or partially closed bye,

Various other objects and advantages of the; corresponding cover so that a space I is formed invention will appear from the following de-; wherein, at appropriate times, the low pressure scription of particular embodiments, of the ine piston Q will produce precompressed air for the vention, in which reference is made to the ac purpose of scavenging and charging the working companying drawing, the novel features being cylinders. 1 v

pointedout in the appended claims. I The interiors of the highand low-pressure In the drawing, the figure illustrates in cross cylinders, A and B respectively are in direct comsection one form of engine embodying the presmunication by the way of the cylinder ports E ent invention. i U y 1, i of the high pressure cylinder and the transfer 1 The engine unit illustrated in the drawing conchannel T, 1

For the purpose of the final evacuation of the completely expanded Working fluid from within the low pressure cylinder B, this latter carries the corresponding valve means H which, in this particular case are shown to consist of rotary-type valves, although any other appropriate type of valve means may be employed for this purpose.

The admission of atmospheric air into the precompression space I is by the way of the valve means G and the precompr'essed air from this space passes at appropriate times into the receiver space R by the way of the valve means U,

it being understood that, although the valve' means G and U are illustrated as being of the poppetand rotary-valve types respectively, any other system. or type of valves may be employed for the purposes of controlling the provision of precompressed scaveningand charging-air necessary for the proper function of this engine.

The axes of the highand low-pressure cylinders form an angle of approximately 45, it

being understood that to secure the proper function of the engine, it is not required that these two cylinders beset at an angle of exactly 45", one with respect to the other, but that their relative angular position may be varied between angular positions of from 20 to about 60, the exact angle beingso chosen with relation to other dead centre position, fuel has been injected by the valve means F and a power stroke initiated, thus the expanding gases will drive the high pressure piston P outward on a working stroke.

At this time the low pressure piston Q is moving inwardly and is driving out the completely expanded gases by way of the corresponding exhaust valve means 1-! and, on the back of said piston Q atmospheric air'is being admitted into the precompression space I through the corresponding valve means G. The exhaust valve means H does not remain open during the entire inward stroke of the low pressure piston Q, so that, during the last portion of its inward stroke, the low pressure piston Q will compress within the cylinder B and transfer channel T a remainder of inert gases, or else an admixture of inert gases and scavenging air, to a pressure that is substantially equivalent tothe pressure at which, at suitable times,the partially expanded working fluid will be released from within the high pressure cylinder A- V I When the high pressure working piston reaches a position of approximately 60 before its bottom dead centre it will uncover the cylinder port openings E, thus establishing a direct communication between the interiors of the highand lowpressure cylinders, byway of the transfer channels, T. 7

As soon as the direct communication between the highand-low pressure cylinders is establis'h'ed the pressures prevailing at that moment within both cylinders as well as the transfer channels will become gradually equalised, although during a short period of time after the initiation of the opening of the cylinder ports E,

or a period that may correspond to approximately 10to 30 crankshaft rotation, the low pressure piston Q may still continue its inward motion.

Somewhat later in the cycle, when the low pressure piston P has reached its inner dead centre position and the maximum back pressure within the low pressure cylinder and transfer channel has thus been attained, the pressures within the highand low-pressure cylinders and the transfer channel will have been completely equalised and, upon the subsequent outward stroke of the low pressure piston Q, the working fluid which continues to pass in a steady flow from within the highinto the low-pressure cylinder renders useful work within this latter, on its second stage expansion and drives the piston Q outward on a working stroke.

During this period of a working stroke within the low pressure cylinder B, the low pressure piston Q will compress on the back thereof, within the space I, atmospheric air to a pressure that, under normal working conditions is equal to the pressure of release of the Working fluid from within the high pressure cylinder A and the air thus compressed is transferred, under the 1 control of the valve means U into the receiver space R in order to be used, to scavenge and charge the high pressure cylinder A for which purpose this latter is provided with the corresponding admission valve means 0.

As far as the scavenging and charging of the high pressure cylinder A is concerned, the valve means will be opened and scavenging air admitted from within the receiver space R, shortly after the initiation of the transfer of the working fluid fromwithin the highinto the low-pressure cylinder, or approximately to 30 crankshaft rotation from the instant when the piston P started to uncover the cylinder ports E, the gas pressure within the high pressure cylinder having dropped to approximately the pressure of the precompressed scavenging and charging air.

The valve means 0 remain open at least for the rest of the period during which the cylinder ports E will also be uncovered and may also be kept open during a short period afterwards if a more accentuated charging or supercharging of the high pressure cylinder A with precompressed air is required, as the case may be.

After the closing of the port openings El and the closing at the same time or else cyclically somewhat later in the cycle, the admission valve means 0 will also have been closed, the inwardly moving high pressure piston P will further compress the intaken charge of air within the high put the interior of the low pressure cylinder B into communication with the exhaust mains or the atmosphere, thus starting the evacuation of the completely expanded working fluid from within the low pressure cylinder B.

Shortly afterwards, the high pressure piston P will have arrived at its pper dead centre position and, with the subsequent injection of a fuel l. A two-stroke compound internal combus tion engine comprisinga high pressure cylinder, a low pressure cylinder with its axis inclined at an acute angle to the axis of the high pressure cylinder, said cylinders enclosing a receiver space in the angle between them, pistons reciprocable in the high pressure and low pressure cylinders, respectively, and connected to the same throw of a crankshaftgan inlet valve through which fluid is admitted for compression in the upper end of the low pressure cylinder, a valve through which the precompressed fluid is passed to a receiver, a valve through which the precompressed fluidis passed from the receiver to the upper end of the high pressure cylinder, means for causing the expansion of the fluid in this end of the high pressure cylinder, a, transfer: passage controlled by the high pressure piston through which the expanded fluid is transferred to the lower end of the low pressure cylinder for a secondary expansion therein, and a valve controlling the exhaust of the fluid from the lower end of1thelow pressure cylinder.

2. A two-stroke compound internal combustion engine comprising a high pressure cylinder,

a low pressure cylinder with its axis inc-lined at an acute angle to the axis of the high pressure cylinder, said cylinders enclosing a receiver space in the angle between them, pistons recylinders, respectively, and connected to the samethrow of a crankshaft, an inlet valve through which air is admitted for compression in the upper end of the low pressure cylinder 3 by the upper face of the low pressure piston, a valve through which the precompressed air is passed to the receiver, a valve through which the precompressed air is passed from the receiver to the upper end of the high pressure cylinder, aninjection valve for injecting fuel into the upper end of the high pressure cylinder for combustion therein, a transfer passage opened by the-high pressure piston towards the end of its working stroke and through which the prodnets of combustion are transferred to the low pressure cylinderfor a secondary expansion beneath thelow pressure piston, and a valve controlling the exhaust of the products of combustion from the lower end of the low pressure cylinder.

3. A two-stroke compound internal combustion engine, comprisinga high pressure cylinder, at low pressure cylinder with its axis inclined to the axis of the high pressure cylinder, pistons reciprocable in the high pressure and low pressure cylinders, respectively, and connected to the same throw of a crankshaft, a short transfer passage between the cylinders opening at one end into the expansion space in the high pressure cylinder and at the other end opening into the lower end of the low pressure cylinder on the under side of the low pressure piston, said passage being controlled by the high pressure piston to transfer the Working fluid towards the piston, a receiver utilizing the space in the angle j between the high pressure and the low pressure ciprocable in the high pressure and low pressure 

